Book: 23227143 (8-24-2010) Rev CPage6
Operational Theory
These machines have an electronic monitor and control system that is used to
provide discharge air pressure control and monitor functions. The system uses
the WEDGE controller to perform these functions. The electrical system connects
all the necessary switches, sensors and transducers to the WEDGE controller in
order for it to perform the monitor and control functions.
WEDGE Controller
The WEDGE controller is the heart of the machine monitor and control system.
It provides data collection, alarming and control functions for compressor
operations. It is a microcontroller based unit with analog and digital inputs and
outputs.
The WEDGE controller is attached to a bracket mounted to the lifting bail inside
the machine over the fuel tank. A laminate is attached to the bracket to identify
the diagnostic lamps and the display.
The first function of the WEDGE controller is to scan all analog and digital inputs
at a fixed interval. These inputs are scanned every 50 milliseconds. The analog
values are then compared against minimum and maximum values and an ALERT
or SHUTDOWN is issued, if a value is out of range. The various ALERTS and
SHUTDOWNS are listed in this manual.
The second function of the WEDGE controller is machine discharge pressure
control. The WEDGE monitors the regulation system air pressure and varies the
engine throttle to maintain the setpoint discharge air pressure. The setpoint
pressure is set using the high pressure regulator and low pressure regulator.
The third function of the WEDGE controller is to communicate with the diesel
engine via the J1939 CAN network. The WEDGE controller retrieves diagnostic
information via the J1939 CAN Network.
The Engine Throttle Setting is sent from the WEDGE Analog Throttle Output to
the engine ECM. The throttle signal range is from 2.5 VDC (1500 rpm) to 3.9
VDC (2200 rpm).The WEDGE controller receives diagnostic and run time data
from the engine ECM over the J1939 CAN network. Figure 2-2 shows the
connections between the WEDGE controller and the engine ECM.
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